Field of the Invention
The present invention relates to a heat pump system in a vehicle. More particularly, the present invention relates to a heat pump system in a vehicle, which embodies heating, cooling and dehumidifying functions with one heat exchanger which also performs a function of an evaporator.
Description of Related Art
In general, an air conditioner in the vehicle includes an air conditioner module for cooling and heating a cabin in the vehicle.
The air conditioner module is configured to cool the cabin with a heat exchange medium owing to heat exchange of the heat exchange medium with the evaporator, or to heat the cabin with cooling water by introducing the cooling water to a heater in a process in which the heat exchange medium discharged as a compressor is driven circulates to the compressor again through a condenser, a receiver drier, an expansion valve and the evaporator.
In the meantime, recently, as people take growing interests in energy efficiency and environmental pollution day by day, development of an environmentally-friendly vehicle which can replace an internal combustion engine vehicle is on demand. The environmentally-friendly vehicle includes, in general, an electric vehicle which is driven taking fuel cell or electricity as a power source, or a hybrid vehicle which is driven by using an engine and a battery.
Of such environmentally-friendly vehicles, different from the air conditioner in a general vehicle, the air conditioner in the electric vehicle has no heater used therein, and the air conditioner applied to the electric vehicle is called, in general, the heat pump system.
Though the heat pump system is the same with a general principle in which, in a room cooling mode in a summer, high temperature and high pressure gaseous refrigerant compressed at the compressor drops a room temperature and humidity by evaporation at the evaporator after passed through the receiver drier and the expansion valve after the refrigerant is condensed at the condenser, in a room heating mode in a winter, the heat pump system uses high pressure gaseous refrigerant as a heater medium.
That is, in the room heating mode, the electric vehicle has the high temperature and high pressure gaseous refrigerant heat exchanging with outdoor air introduced, not to an outdoor condenser, but to an indoor condenser, through a valve such that the outdoor air heat exchanged thus makes a temperature of the vehicle cabin to rise as the outdoor air is introduced to the cabin of the vehicle while passing through a PTC (Positive Temperature Coefficient) heater.
And, the high temperature and high pressure gaseous refrigerant introduced to the indoor condenser is condensed as the refrigerant heat exchanges with the outdoor air and discharged as liquid refrigerant, again.
However, though the related art heat pump system is required to include a dehumidifying mode for removing moisture from a window of the vehicle in middle of operation of a cooling mode in a summer or a heating mode in a winter, in order to operate the dehumidifying mode, it is required to add a heat exchanger to the heat pump system. Consequently, a problem is caused, in that an entire system package increases due to addition of an element and complicated pipe layout, and a production cost increases.
Moreover, if the heat exchanger is provided to the cabin, mounting of 3-way valves on pipelines is required, to open/close the valves frequently causing noise and poor durability, and the increased pipelines causes a large pressure loss with a poor overall NVH (noise vibration harshness) performance.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.